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US 6,635,931 B1Granted
Bonding pad-oriented all-mode ESD protection structure
AssigneeIllinois Institute of Technology
InventorAlbert Zihui Wang
Life of this patent
Estimating the term…
Abstract
An all-mode, bonding pad-oriented ESD (electrostatic discharge) protection structure, protects ICs against ESD pulses of all modes in all directions. A unique quasi-symmetrical layout design is devised to improve ESD structure. Physical symmetry and rounded layout provide uniform current and thermal distribution as well as symmetrical electrical operation characteristics. The ESD structure allows tunable triggering voltage, low holding voltage, low impedance, low leakage, fast response time and low parasitic effect. The ESD structure can easily be placed under or surrounding a bonding pad and consumes little extra silicon. The ESD structure can be implemented in commercial BiCMOS processes and is suitable for multiple-supply, mixed-signal, parasitic-sensitive RF and high-pin-count ICs.
Claims20
An ESD protection structure for an internal circuit of an Integrated Circuit (IC) comprising:
- a circuit having subcircuits providing an active devices in each ESD discharge mode, namely ND, PD, PS, NS, DS, and SD;
- and the circuit comprised of a structure having:
- a) a central construction having:
- i) a first diffusion of a first type and
- ii) the first diffusion surrounded over first and second lengths of its circumference by first and second inner diffusions of a second type, the first and second inner diffusions being separated by first and second areas of insulating material;
- b) a distal construction surrounding the central construction and having:
- i) a moat of insulating material surrounding the central construction, the moat including the first and second areas of insulating material between the first and second inner diffusions,
- ii) a second level construction outside of the moat including third and fourth diffusions of the second type, the third and fourth diffusions of the second type occupying the areas surrounding the first and second areas of insulating material of the central construction;
- and first and second half rings being diffusions of the first type, the first and second half rings being distal from and adjacent each of the third and fourth diffusions of the second type, and the first and second half rings being separated from each other by areas of insulating material connected to the moat, each of the first and second half rings surrounding about half of the central construction and about half of the moat, said half of the central construction including one of the first and second diffusions of the second type of the central construction and one of the first and second areas of insulating material.
6 more elements
An ESD protection structure for an internal circuit of an Integrated Circuit (IC) comprising:
- a circuit having subcircuits providing an active device controlling each ESD discharge path, namely ND, PD, PS, NS, DS, and SD;
- and said circuit comprising:
- a) a central construction having:
- i) a central well of a first conductive type having therein a central diffusion of a first type, and
- ii) the central diffusion surrounded over first and second about-quarter lengths of its circumference by first and second inner diffusions of a second type, respectively, at opposite sides of the central diffusion circumference;
- the first and second inner diffusions being separated by first and second about-quarter length areas of Field Oxide insulation;
- b) a distal construction surrounding the central construction and having:
- i) a moat of Field Oxide insulation surrounding the central construction, the moat including the first and second about-quarter length areas of Field Oxide insulation between the first and second inner diffusions,
- ii) a second level construction outside of the moat including second and third wells of the first conductive type having third and fourth diffusions of the second type, the third and fourth diffusions of the second type occupying the areas surrounding the first and second about-quarter length areas of Field Oxide insulation of the central construction, and
- first and second half rings being diffusions of the first type, the first and second half rings being distal from and adjacent to each of the third and fourth diffusions of the second type, and the first and second half rings being separated from each other by areas of Field Oxide insulation connected to the moat, each of the first and second half rings surrounding about half of the central construction and the moat, said half of the central construction including one of the first and second diffusions of the second type of the central construction and one of the first and second about-quarter length areas of Field Oxide insulation.
7 more elements
An ESD protection structure for an internal circuit of an Integrated Circuit (IC) comprising:
- a circuit providing an SCR in each ESD discharge path, and the circuit comprised of a substantially bilaterally symmetrical structure having:
- a) a central construction having:
- i) a central well of a first conductive type having therein a central diffusion of a first type, and
- ii) the central diffusion surrounded over first and second about-quarter lengths of its circumference by first and second inner diffusions of a second type, respectively, at opposite sides of the central diffusion circumference, the first and second inner diffusions being separated by first and second about-quarter length areas of Field Oxide insulation;
- b) a distal construction surrounding the central construction and having:
- i) an unbroken moat of Field Oxide insulation surrounding the central construction,
- ii) a second level construction outside of the moat including second and third wells of the first conductive type having third and fourth diffusions of the second type, the third and fourth diffusions of the second type occupying the areas surrounding the first and second about-quarter length areas of Field Oxide insulation of the central construction, and
- first and second half rings being diffusions of the first type, the first and second half rings being distal from, and adjacent to, each of the third and fourth diffusions of the second type, and the first and second half rings being separated from each other by areas of Field Oxide insulation connected to the moat, each of the first and second half rings surrounding about half of the central construction and the moat, said half of the central construction including one of the first and second diffusions of the second type of the central construction and one of the first and second about-quarter lengths areas of Field Oxide insulation.
5 more elements
Dependencies are inferred from the claim text.